1. Field of the Invention
The present invention relates to a brake disk for bicycles, especially to a brake disk for bicycles with high abrasion resistance, high temperature resistance and low heat conduction.
2. Description of the Prior Arts
A bicycle is a very common vehicle. Some bicycles have a disk brake system, and the disk brake system has a brake disk and two disk brake pads. The brake disk is mounted on the hubs of the bicycle, and the disk brake pads are respectively mounted on the both sides of the brake disk. When the user operates the disk brake system, the disk brake pads move inside and clamp the brake disk. With the friction between the disk brake pads and the brake disk, the wheel stops rotating gradually.
Bicycles tend to get light-weighted currently, and the components of the bicycles are made of light materials, such as carbon fiber or light alloy like aluminum alloy. The brake disk is made of those materials as well. However, the friction between the disk brake pads and the brake disk causes high temperature, and the carbon fiber has low abrasion resistance and low temperature resistance, so the carbon fiber is not suitable to rub against the disk brake pad. As a result, the brake disk is divided into two outer disks and an inner disk. The outer disks are used to rub against the disk brake pads, so the outer disks are made of metal. The inner disk is clamped between and glued to the outer disks, so the inner disk is made of carbon fiber to reduce the whole weight.
However, this brake disk has the following shortcomings
Although the outer disks are made of metal, the deformation resistance of the outer disks is not good enough. The thickness of the outer disks is too thin, so the outer disks still may deform.
Additionally, metal can conduct heat easily, so the heat generated by friction would be quickly transmitted to the inner disk, and makes the glue between the inner disk and the outer disks melt and lose its function. Then, the inner disk and the outer disks depart from each other and the whole brake disk is broken.
Manufacturers have invented a brake disk made of material with high abrasion resistance, high temperature resistance, and low heat conduction, such as silicon carbide ceramic. However, said certain material is hard to obtain, and the brake disk made is too thin and therefore too fragile.
To overcome the shortcomings, the present invention provides a brake disk for bicycles to mitigate or obviate the aforementioned problems.